Steiner and Granger: Retirement rules of thumb

Because retirement rules of thumb are guidelines designed for the average situation, they'll tend to be "wrong" for a particular retiree as often as they're "right."

However, rules of thumb are usually based on a sound financial principle, and can provide a good starting point for assessing your retirement needs. Here are four common retirement rules of thumb.

The percentage of stock in a portfolio should equal 100 minus your age
Financial professionals often advise that if you're saving for retirement, the younger you are, the more money you should put in stocks. Though past performance is no guarantee of future results, over the long term, stocks have historically provided higher returns and capital appreciation than other commonly held securities. As you age, you have less time to recover from downturns in the stock market.

Therefore, many professionals suggest that as you approach and enter retirement, you should begin converting more of your volatile growth-oriented investments to fixed-income securities such as bonds.

A simple rule of thumb is to subtract your age from 100. The difference represents the percentage of stocks you should keep in your portfolio.

For example, if you followed this rule at age 40, 60% (100 minus 40) of your portfolio would consist of stock. However, this estimate is not a substitute for a comprehensive investment plan, and many experts suggest modifying the result after considering other factors, such as your risk tolerance, financial goals, the fact that bond yields are at historic lows, and the fact that individuals are now living longer and may have fewer safety nets to rely on than in the past.

A "safe" withdrawal rate is 4%
Your retirement income plan depends not only upon your asset allocation and investment choices, but also on how quickly you draw down your personal savings.

Basically, you want to withdraw at least enough to provide the current income you need, but not so much that you run out too quickly, leaving nothing for later retirement years. The percentage you withdraw annually from your savings and investments is called your withdrawal rate. The maximum percentage that you can withdraw each year and still reasonably expect not to deplete your savings is referred to as your "sustainable withdrawal rate."

A common rule of thumb is that withdrawal of a dollar amount each year equal to 4% of your savings at retirement (adjusted for inflation) will be a sustainable withdrawal rate. However, this rule of thumb has critics, and there are other strategies and models that are used to calculate sustainable withdrawal rates.

For example, some experts suggest withdrawing a lesser or higher fixed percentage each year; some promote a rate based on your investment performance each year; and some recommend a withdrawal rate based on age.

Factors to consider include the value of your savings, the amount of income you anticipate needing, your life expectancy, the rate of return you anticipate from your investments, inflation, taxes, and whether you're planning for one or two retired lives.

You need 70% of your preretirement income during retirement
You've probably heard this many times before, and the number may have been 60%, 80%, 90%, or even 100%, depending on who you're talking to. But using a rule of thumb like this one, while easy, really isn't very helpful because it doesn't take into consideration your unique circumstances, expectations, and goals.

Instead of basing an estimate of your annual income needs on a percentage of your current income, focus instead on your actual expenses today and think about whether they'll stay the same, increase, decrease, or even disappear by the time you retire. While some expenses may disappear, like a mortgage or costs for transportation to and from work, new expenses may arise, like yard care services, snow removal, or home maintenance--things that you might currently take care of yourself but may not want to (or be able to) do in the future.

Additionally, if travel or hobby activities are going to be part of your retirement, be sure to factor these costs into your retirement expenses. This approach can help you determine a more realistic forecast of how much income you'll need during retirement.

Save 10% of your pay for retirement
While this seems like a perfectly reasonable rule of thumb, again, it's not for everyone. For example, if you've started saving for retirement in your later years, 10% may not provide you with a large enough nest egg for a comfortable retirement, simply because you have fewer years to save.

However, a related rule of thumb, that you should direct your savings first into a 401(k) plan or other plan that provides employer matching contributions, is almost universally true. Employer matching contributions are essentially "free money," even though you'll pay taxes when you ultimately withdraw them from the plan.

Past performance is no guarantee of future results. Market indices listed are unmanaged and are not available for direct investment. All investing involves risk, including the risk of loss of principal, and there can be no guarantee that any investment strategy will be successful. The Dow Jones Industrial Average (DJIA) is a price-weighted index composed of 30 widely traded blue-chip U.S. common stocks. The Standard & Poor's 500 is a market-cap weighted index composed of the common stocks of 500 leading companies in leading industries of the U.S. economy.